I don't think this is a bad thing. This is duck-typing at work to be flexible where the type doesn't really matter, just the provided interface. If someone happens to provide an object that doesn't do the right thing then that's their fault for using the wrong object and the resulting exception that will occur from a bad path is acceptable.

I appreciate the work to do a PR, Oren, but I'm closing this issue as "rejected". (And if it makes you feel any better, you helped find a bug in the Bedevere bot. :) .